John's Living Bread Discourse (John 6:35-58) has two parts. The first part (vv. 35-50) has a sapiential theme: the living bread is the teaching of Jesus. The second part (vv. 51-58) is sacramental; here, the living bread is Jesus himself. Raymond Brown has this to say:
to bring out the deeper sacramental meaning of the heavenly bread (which could be seen only after the institution of the eucharist) the Johanine redactor has combined the bread of heaven with eucharistic material from the Last Supper and so formed the second part of the speech as a parallel to the first. This accounts for John's omission of the institution of the eucharist at the Last Supper; its substance has been moved here.
(The Gospel and Epistles of John: A Concise Commentary, p. 45)
The selection proposed by the liturgy covers part of the sapiential discourse and concludes with the first line of the eucharistic discourse (v.51)
In verse 45-50, Jesus answers the murmuring of the Jews. As the Israelites murmured in the desert on account of the manna, so too, the Jews show their resistance to Jesus by murmuring. Jesus' objection begins with a quotation from Isaiah 54:13, which is found in a context that speaks of a New Zion that God will rebuild. A covenant of peace between God and his people will characterize this new state of being, and all will be taught by God himself. Jesus responds to the murmuring of the Jews by saying, in effect, "Take it or leave it." Those who truly learn from God would go to him.
In verse 50 is echoed John 1:18:
No one has ever seen God.
The Only Son, god, who is at the Father's side, has revealed Him.
In verse 48, Jesus identifies himself as the Bread of Life that gives eternal life (vv. 48-50).
The description of the Bread of Life "come down from heaven" echoes earlier pronouncements that Jesus makes about himself:
In John 1:51, he tells Nathanael: "You will see the sky opened and the angels of God ascending and descending (going up and down) on the Son of Man." The reference is to Jacob's vision of the stairway to heaven at Bethel. Jesus is in effect saying that God's revelations will be passing through Him while at the same time, men's supplications will be carried to God through him.
In John 3:13 Jesus tells Nicodemus: "No one has gone up to heaven except the one who has come down from heaven, the Son of Man." Jesus is the mediator between heaven and earth. It is he who makes possible the rebirth from above which makes possible the entrance to God's kingdom. to believe in him (the Son of Man) is to have eternal life.
Thus, the one who comes down from heaven is the key to eternal life. Those who receive him receive life that is "from above." Only thosse who have allowed themselves to be taught by God are led to Him. Finally, in verse 51, Jesus introduces the topic of the eucharist. He is the Living (note the change in the adjective) Bread
Whoever eats this bread
will live forever;
and the bread that I will give
is my flesh for the life of the world.
The Word of God was made flesh and dwelt among us. Now however, what was made flesh is offered asw Bread for the life of the world. Word, flesh, Bread: the incarnation continues in the Eucharist.
